Spike Jones, <spike66@ibm.net>, writes:
> the thought was incorrect too: there may be other more radioactive
> isotopes more suitable for tiny reactors than plutonium. i didnt think
> it thru carefully enough. i guess thats what the concept of nanotech
> does to one: opens ones mind a bit. {8-]
I have seen the size of the nucleus relative to the size of the atom as being comparable to the size of a fly relative to the size of a football stadium. Imagine trying to shoot two football stadia at each other with enough accuracy that the flies in the middle hit, especially when the flies repel each other. This is the difficulty of fusion by atomic collision.
With compression, we have a collection of football stadia, and a compression wave comes in from the outside, squeezing the stadia together. You can see that the compression has to be extremely strong in order to get two flies near each other, and even then you probably need a lot of stadia involved to improve the chances. This is the difficulty of fusion by compression.
With fission, a fly splits, and some sub-fly-sized particles go flying out. Clearly with two atoms near each other, the chance of one fly particle hitting the fly at the middle of the other is extremely remote. That is why you normally need a whole lot of stadia, so that there is some reasonable chance of a fly particle happening to strike another fly at such distances. This is the difficulty of fission by critical mass.
Various tricks have been proposed to improve the situation. With muon catalyzed fusion, the size of the atoms is reduced by replacing the electrons with muons. Instead of a fly in a football stadium, it's like a fly in a closet. Now there is a significant possibility for flies in adjacent closets to get near each other, although you still probably need a large number of atoms to give you good odds.
Cold fusion was supposed to inject more flies into the system, but clearly even if we could increase the density of flies by a factor of 2 or even 10, the rate of fusion would still be very small, and again you would need a lot of atoms.
Maybe some tricks could be used to help with fission. If we could somehow control the direction of the fly particles, we might increase the chance of them hitting other flies. Maybe some quantum tricks, magnetism or something similar, could help with that. I haven't heard of any research along those lines.
Hal